Instability Mechanism Of Inner Dump Slope Under Water Rich Mudstone Basement And Waste Material

Heavy rainfall and groundwater are the important reasons for the landslide and instability of the dump in the open-pit mine.Rainwater or groundwater infiltrates into the waste materials and the basement stratum,which accelerates the deformation and destruction of the slope,especially the slope of the dump with hydrophilic minerals such as mudstone in the basement.Once the slope is unstable,it will cause serious economic losses and casualties.At present,there are few studies on the slope stability of the flooded mudstone basement,and there are few reports on the slope stability under the combined action of the flooded mudstone basement and the rich water of the discarded materials.Based on this,this paper takes an open-pit mine Inner Dump as the engineering background,adopts the methods of field measurement,theoretical analysis,numerical simulation and laboratory test to carry out the research on the mechanism of slope instability under the action of water rich of water soaked mudstone base and inner dump.The main conclusions are as follows(1)Based on the engineering geological drilling and trenching engineering,the lithology of the dumping site layer in open pit mine is obtained,which is from top to bottom as follows: dumping material layer,weak mudstone layer,sandy mudstone layer and siltstone layer;the hydrogeological conditions show that the basement and dumping material of the inner dumping site are mainly affected by the lateral recharge of surface water and groundwater in the east side,and the parameters of the basement and dumping material may decrease small,the induced slope landslide.(2)Combined with the results of laboratory tests,the parameters of rock and soil are determined.Among them,the saturation range of waste material is 63.422% ?68.525%,which is relatively wet(60% ? SR ? 70%),and the saturation of weak mudstone layer is above 92%,reaching nearly saturated state(SR > 80%),which indicates that the basement of yiminnei dump has large water content;the cohesion and internal friction angle of weak mudstone layer decrease nonlinearly with the increase of water content And the internal friction angle decreases linearly with the increase of water content.(3)This paper discusses the factors influencing the accuracy of slope safety factor in PHASE2,analyzes the influence of water content,thickness and dip angle of mudstone weak layer on the displacement field,maximum shear strain and safety factor of Inner Dump Slope,and reveals the deformation and instability mechanism of Inner Dump Slope on the basis of water soaked mudstone from the engineering point of view.(4)Based on Mohr Coulomb failure criterion and limit equilibrium principle,the mechanical model of the ultimate bearing capacity of the inclined foundation is established considering the influence of the foundation inclination.The shape of the bearing area of the foundation and the load characteristics of each characteristic area are discussed in detail,and the eigenvalues of the foundation bearing capacity are studied.The approximate calculation formulas of the critical thickness of the weak layer of the foundation and the ultimate bearing capacity are derived The response law of the water content of mudstone weak layer to the critical thickness of the base and the safety factor of the slope is analyzed,and the calculation results are verified.The influence of the water content of the base and the inclination angle on the safety factor of the slope is revealed from the mechanical point of view.(5)The influence of water content and height of waste materials on the displacement field,maximum shear strain and safety factor of slope is analyzed by using PHASE2 software.The mechanism of slope instability under the combined action of water rich mudstone base and inner dump is revealed from the engineering point of view.This paper has 66 pictures,28 tables and 94 references.